Enhanced Integration of Newborn Neurons after Neonatal Insults

The production and integration of adult-generated neurons in the dentate gyrus is dramatically perturbed by a variety of pathological insults, including repetitive seizures and hypoxia/ischemia. Less is known about how insults affect early postnatal neurogenesis, during the developmental period when the majority of dentate neurons are produced. Here we tested how single episodes of hypoxia or chemically induced seizure activity in postnatal day 10 mice alter granule cell production and integration. Although neither insult was sufficient to alter the number of newborn neurons nor the population of proliferating cells, both treatments increased the dendritic complexity of newborn granule cells that were born around the time of the insult. Surprisingly, only the dendritic enhancement caused by hypoxia was associated with increased synaptic integration. These results suggest that alterations in dendritic integration can be dissociated from altered neural production and that integration appears to have a lower threshold for perturbation. Furthermore, newborn neurons in adult mice that experienced neonatal hypoxia had reduced dendritic length while having no alterations in number. Together these results suggest that single insults during the neonatal period can have both long- and short-term consequences for neuronal maturation

Kinematics of the CO Gas in the Inner Regions of the TW Hya Disk

We present a detailed analysis of the spatially and spectrally resolved 12CO J=2-1 and J=3-2 emission lines from the TW Hya circumstellar disk, based on science verification data from the Atacama Large Millimeter/Submillimeter Array (ALMA). These lines exhibit substantial emission in their high-velocity wings (with projected velocities out to 2.1 km/s, corresponding to intrinsic orbital velocities >20 km/s) that trace molecular gas as close as 2 AU from the central star. However, we are not able to reproduce the intensity of these wings and the general spatio-kinematic pattern of the lines with simple models for the disk structure and kinematics. Using three-dimensional non-local thermodynamic equilibrium molecular excitation and radiative transfer calculations, we construct some alternative models that successfully account for these features by modifying either (1) the temperature structure of the inner disk (inside the dust-depleted disk cavity; r < 4 AU); (2) the intrinsic (Keplerian) disk velocity field; or (3) the distribution of disk inclination angles (a warp). The latter approach is particularly compelling because a representative warped disk model qualitatively reproduces the observed azimuthal modulation of optical light scattered off the disk surface. In any model scenario, the ALMA data clearly require a substantial molecular gas reservoir located inside the region where dust optical depths are known to be substantially diminished in the TW Hya disk, in agreement with previous studies based on infrared spectroscopy. The results from these updated model prescriptions are discussed in terms of their potential physical origins, which might include dynamical perturbations from a low-mass companion with an orbital separation of a few AU.Comment: 30 pages, 7 figures, accepted for publication in Ap

Long term monitoring of Integral sources with Swift/BAT

International audienceINTEGRAL has discovered many previously unknown hard X-ray sources, particularly in the Galactic plane. Typically the INTEGRAL observations are deep but the sources are within the field of view only for a comparatively short time. A given sky direction is usually within the field of view of the BAT instrument on Swift 10% of the time and 85% of the sky is usually observed every day. Thus BAT is able to provide complementary hard-X-ray information on the long-term behavior of sources. We report new results on INTEGRAL and other sources, including orbital, super-orbital and other periodicities and spectral evolution histories

GABAergic signalling to adult-generated neurons

New neurons are continuously generated in discrete regions of the adult brain. In the hippocampus, newly generated cells undergo a step-wise progression of maturation that is regulated at multiple stages by a variety of physiological and pathological stimuli. Neural progenitors and newborn neurons initially receive exclusively GABAergic synaptic input, and accumulating evidence suggests that depolarizing actions of GABA contribute to activity-dependent regulation. Here we provide a brief overview of GABAergic signalling to newborn neurons in the hippocampus and describe how it regulates adult neurogenesis